Picture frame



FIG. 1 is a left perspective view of a picture frame showing my new design;

FIG. 2 is a front view of the picture frame of FIG. 1;

FIG. 3 is a top view of the picture frame of FIG. 1, the bottom view being identical;

FIG. 4 is a left side view of the picture frame of FIG. 1, the right view being identical; and,

FIG. 5 is a back view of the picture frame of FIG. 1.

The broken lines in FIGS. 1-4 represent environmental subject matter and form no part of the claimed design. 

The ornamental design for a picture frame, as shown and described. 